Freedom of information (FOI) requests by the Press Association to the 43 forces revealed that two-thirds of cases involved police officers and 9 per cent ended in resignation, dismissal or retirement.
Examples of incidents uncovered by the FOIs include a civilian officer commenting on Facebook about Muslims in London not observing a two-minute silence, and a Devon & Cornwall Police community support officer in who posed with weapons and posted the pictures online.
The force that conducted the greatest number of investigations, Greater Manchester Police, did not suspend or sack any staff involved.
Its director of corporate comms Amanda Coleman told PRWeek that just three of the 88 incidents investigated involved official police accounts and off-duty use was the main issue.
"The problems that arise are often in people’s personal use, where people will say and do things as they would while having a conversation down the pub. We have very few issues with staff trained to use social media at work."
More than 350 staff, from a total around 11,000, had gone through training to handle specific social media accounts for the force, she said, adding that the force is the third biggest in the country.
Efforts to alert staff to the fact that that police codes of ethics extended to out-of-hours conduct were ongoing, she said, and included a video highlighting the potential dangers of personal social media use. However, she acknowledged that these efforts were counterbalanced by increasing numbers of staff using the medium.
"There are more people aware of the standards expected," she said, "but over the last four years there has been a massive increase in people using social media, so for us these efforts are the starting point."
The force that conducted the second highest number of investigations was West Midlands Police with 74, ahead of the Metropolitan Police with 69.
Danny Whatmough, PRCA digital chairman, welcomed the action taken by police forces against breaches of guidelines, stating that "inappropriate tweets" were "hugely damaging to reputation".
Highlighting recent PRCA research which revealed 89 per cent of organisations now have a specific social media policy for employees, he added organisations nonetheless often "overlook" the policing of such policy.
"Among the most prone to breaches are those in the public sector, which feature large numbers of dispersed employees," he said.